That was sometime in 1994, involving services like 124, 143
& 952 etc. Transponders on these buses communicated with
antenna affixed on traffic lights, which will calculate the time
needed to reach the next bus stop by adjusting the traffic
lights.
A similar priority traffic scheme was later applied along the old
RapidBus 700 route from Woodlands to Shenton Way, by allowing the
bus to have priority in clearing selected traffic light junctions.
Upon detection of an oncoming RapidBus, the traffic light will
either lengthen the green timing by 10 seconds or shorten the red
waiting time by 10 seconds.
It was eventually abandoned, before the GLIDE system was
progressively extended to control all traffic light junctions.